OZbrick quick tip: If you seem to have indicator flashing cycles interrupted, perhaps intermittently, but there is nothing wrong with the exterior lights and you have checked the bulb terminals, then the hazard switch itself may be playing up. It may not be necessary to replace it; just gently slide it out (the hazard switch and flasher can are integrated) and disconnect it at the rear. Then spray the hell out of it with WD-40, making sure to get plenty into the unit via every orifice available. Shake it to get out any excess & dry the whole exterior, reconnect and insert it back into the car. This should help to clean the flash contacts, and within a little while the unit should be back to normal...

Re: Bad Blinker and Noises [S70][2000] ... posted by Vladimir  on Sunday, 10 December 2000, at 8:15 p.m.
...in response to "Bad Blinker and Noises" posted by Don.

                      Don, here's what I know.

                      > 1)Recently my right blinker started blinking twice as fast as the
                      > left.. They both work but it just blinks much faster.. Anyone know
                      > what might be causing that?

                      You are experiencing a well-known problem/condition. Due to a design flaw there is too much current
                      going through one of the contacts in those lamps. Because of that there is some sparking and carbon build
                      up on the offending contact. There is avery simple DIY solution for this. Take the turn signal assembly out
                      (it's easy, look in the owner's manual), remove the bulb. You will recognize the contact that caused the
                      problem by carbon biuld up and, in some cases, melted plastic in the base of the bulb. Clean the contact
                      with a swiss army knife blade or something like that and make sure the corresponding contact in the socket
                      is also clean. Re-insert the bulb turning it 180 degrees around its long axis so that the charred contact
                      mates with the opposite end of the one it used to mate with (there is no polarity for the bulbs). Re-install
                      the assembly -- you are now good for another year or so. While the car is under warranty the dealer will
                      replace your bulbs and sockets for you for free, but if you'd rather avoid a trip to the dealer, you know
                      what to do now. There is talk of the recall for this problem but it hasn't been announced yet.

                      > 2) When the car warms up I hear this "moaning" sound from
                      > under the hood..increases as RMP's increase and when I turn the
                      > steering wheel it gets louder..its definitely related to the belts/
                      > and what it drives. Can this be the power steering pump?

                      Check the level of the power steering fuid. Chances are it is too low. Top it off and the moaning will stop.

                      Sorry, can't help with no. 3

                      --
                      Vladimir. Base 1998 S70 5-speed manual.

Hmmm... Seems to be my weekend of disaster re. the volvo... 1976 244dl for those
who aren't already acquainted with it... Had the "bulb failure warning light"
come on... strange since all of the bulbs are aok.. checked
* Brake
* Reversing
* Day running tail lights
* Day running front lights
* Parkers
* Headlights
* Number plate lights
* Blinkers

Any ideas anyone? Also, at the same damn time that this happened, my blinkers
have been playing up. Flasher can? Who knows. Sometimes the seat belt warning
light flashes, sometimes not. Sometimes the blinkers work fine, other times not.
The hazard lights always seem to work fine.

As for the bulb failure warning, I pulled the relay, (which of course made the
light go out), nothing obvious to a halfwit like me (ie soot blackened exterior,
heavily melted case and so on), so I put it back.

Question: Is this just coincidence / are the two related in some way?

Help please. Thank you muchly.

Owen in Australia

Owen,
You need to look at your grounds for all of your lighting closely. The bulb sensor checks low beams, tail lamps, and brake lamps. Any other lights that make the bulb come on are indicative of faulty grounds. Rear grounds are adjacent to tail lamp assemblies and front grounds are inner panels 6-8 inches below fender edge and 5-6 inches behind core support panel. I believe the wires will be secured by phillips screws on your model.

As I recall, the bulb integrity sensor compares the amp(I think) load between the head lights, tail lights, and brake lights, respectively. A mismatch illuminates the sensor.

My current (no pun intended) situation is that my brake light bulbs are the correct wattage, but are of different manufacture. Result: When I depress the brake pedal, the warning light illuminates momentarily. Annoying, but not fatal. The solution is for me to shut off this damn computer and get to work on my car!

The bottom line: It may be worth checking that all sensed lights are of the same wattage and manufacturer to ensure there is no ampere mismatch.

Heck, it's worth a shot.

OTOH, an awful lot of instrumentation problems can be traced to loose ground connections behind the instrument cluster. Happened to me.

Good Luck

The bulb integrity sensor is an electrical device known as a Wheatstone Bridge. The critical bulb circuitry for the car is divided into left and right circuits (this is why it's tricky to hook up trailer lamps) each running through separate coils in the sensor. Current (amps) drawn though the left side circuitry is wound one way and from the right side the opposite way. With a little magnetic contact leaf running up the middle, if either side current is significantly different from the other then the magnetic fields do not cancel each other out and the leaf contact pulls off center to make contact for the bulb integrity sensor dash lamp to go on. (please forgive my wording if that's not crystal clear the first time you read it) At least this is the way Bosch used to do it, they may have moved to solid state cicuitry on the newer cars, but the principle is the same.

All that being said, it only matters that the current draw left and right though the bulbs is matched. If you want to you use the wrong wattage bulb on one side, then do the same on the other.

If you're having trouble with the bulb integrity sensor (such as flashing on when braking) then you need to match both the load and the response characteristic of the left and right side bulbs:

• Check/clean the base of the bulb and the socket contacts (with power OFF unless you enjoy sparks and have spare fuses). This is where I've found the majority of sensor problems.
• Check/clean the bulb socket ground to chassis ground connection (clean to bare metal if needed).
• Use dielectric grease on all connections if you are having corrosion problems. A good auto-marine electrical supply house should have this under the Permatex (Loctite) or other label. I consider this a basic item in my Volvo first aid kit so get the jumbo size (it's useful for everything from fuse panel problems to ignition/injection control module connections).
• Check/clean the wiring harness connections.
• Try swapping bulbs left/right or even with another car.
• Match bulb numbers and manufacturer (although even within a brand there can be subtle differences in the tungsten filament from batch to batch).

If all else fails you can try adjusting the Wheatstone Bridge with a variable resistor (I think the old sensors even had an accessible adjusting screw), but this really
shouldn't be necessary.

Thanks daves and Abe...

Turns out that I at some time replaced a blown 5W visibility light (tail)
with a 21W indicator bulb.... Hence the difference in amperage, etc.

Works great now.

By the by, the flasher can problem turned out to be just a faulty flasher
can... easy fix, done now.

Thanks people..

Owen in Australia